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Description t name of the invention
Loudspeaker system
DETAILED DESCRIPTION OF THE INVENTION The present invention relates to loudspeaker
systems, and in particular to systems capable of reproducing high accuracy and distortion free
speech. Traditionally, most loud, low distortion loudspeakers capable of reproducing sound in the
35 to 40 cycles / second range have low frequency speakers (hereinafter referred to as woofers)
directed to the listener. The diameter of the cone of this woof f- is at least 25. atM to 505c? F +
(10 to 12 inches), the innermost 7.6 cm or 1 alpha 2 cm (3 or 4 inches) range of this cone is
constructed due to the stress created in the cone by the heavy force from the woofer's voice coil
Strained. This structural distortion produces a disturbing degree of reproduced speech distortion.
Although this distortion is slight, it occurs within the 500 to 1500 ep− frequency range, which
is the lower part of the lowest frequency range heard by the human ear, when measured for the
full power of the speaker system. This distortion (below, produces an intermittent squeaky sound,
especially at the mid frequencies of instruments such as central cone distortion orin.
Conventionally, in order to eliminate this central cone distortion, various types such as providing
an electrical crossover network that eliminates the frequency of 500 cps or more from the
woofer, and providing a large mid-range speaker capable of reproducing the sound of iC 500 cps
or less Proposal was made. However, even if such a method is adopted, a ghost of considerable
central cone distortion appears in the woofer L, and the central cone distortion of its own is at
the upper end of the frequency band most sensitive to human ears. Expensive to generate).
Depending on the specific design of the large mid-range speaker, the occurrence of central cone
distortion in the low range of 4000 to 6000 cps or possibly 2500 epa is expected. Attempts have
been made to remove central cone distortion from the speaker system by mounting a damper
member in the central region of the woofer cone. The addition of a damper to the woofer cone is
contrary to the basic principle of a low strain woofer that keeps the inertia of the cone
mechanism as low as possible. したがって。 The added components have the disadvantage of
causing significant distortion of the woofer at significantly lower frequencies. Another problem
with conventional loudspeaker systems is that the high frequency shifts more linearly and needs
to be reflected to turn the corners, resulting in poor sound distribution at the top of the
frequency range covered by the woofer It is to become.
This effect is significant at about 500 'eps or more. Conventional. Various loudspeaker systems
used woofers provided to shut off at 1000 to 1500 ep8. The linearity of the propagation of the
frequency which these woofers emit at 500 to 1500 epl + forms a narrow band along this
frequency or the axis of the loudspeaker. While the distribution of these frequencies is worse,
frequencies below 500 cps have better distribution due to their non-linearity. Another problem
with conventional loudspeaker systems. It relates to the shape of the response curve of the
woofer. Ideally, the highest volume of playback should be generated at the lowest audio
frequency. However, in practice, most good quality woofers have a peak or [June point J (Knee)
in the response curve at the highest t of the sound, which occurs at about 1000 cps, due to
distortion in the middle of the cone. This peak or overhang, which appears just below the
crossover point between the woofer and the midrange speaker, produces metallic noise which
can hardly be solved in the above-mentioned electrical crossover network. Because the frequency
range most sensitive to the human ear is the frequency between 1000 and 3000 eps, the woofer
can be cut off at about 1000 epl, mid-range speakers can take over at about 1000 cps, and a
small, low inertia cone has the highest volume It is preferable to reproduce the frequency and to
make the distortion sound as inaudible as possible. In order to solve the problem of central cone
distortion, the strength of the cone EndPage: 2 is improved by using a cone in which the
nonmetal layer is sanded in between the inner and outer metal members to eliminate the above
mentioned distortion It was suggested to do. The Hitachi metal cone loudspeaker (issued in
October 1-97, described on page 12 of the Stereo Review Magazine) is a speaker of this type.
Tanoy's speaker (issued in June 1977, Stereo Review, page 107) is a speaker cone using rib
members to prevent stress-induced cone breakage or distortion. Another attempt to avoid central
cone distortion has been to use strong carbon fibers in the paper cone. From the outer end of the
cone to the voice coil weir at the center of the cone, there are at least the following six factors
that increase the stress in the loudspeaker cone. (1) The area of the cone is increased by the
second power of the oblique height of the cone.
Thus, the resistance of the air to the movement of the cone is increased by the second power of
the oblique height of the cone. 2) In the outer part of the cone, half waves of the sound wave are
simultaneously generated so that the inner part of the cone can not only resist the force of air
but also the force from the outer part. It is necessary to add another first power because a
compression or tensile force is given along the oblique height. (6) Since the cross section of the
paper cone which needs to transmit the force to the voice coil reduces the height of the diagonal,
the stress of this mechanism is the same as the voice coil side along the diagonal height of the
cone. Increase as the power of As mentioned above, the stress along the cone's oblique height
increases as it travels towards the voice coil from the outside of the cone as at least a 4 to 4
power. The total combined compressive force in a paper cone of about Q, 25 W (about 0.01 inch)
thick is greater than or equal to 0.45 kl (one pound) near the center of the cone. This results in a
unit stress on the order of 10 k (20 bonds) per 2.54 cf11 square (one inch square). This is
considered to be a very small unit stress, but it is sufficient to compress the internal 2.54 inch (1
inch) slope distance by approximately 10064 gardens. However, since there is a fourth power to
generate stress that greatly reduces the distance in the direction away from the voice coil, 2.54
cm (one inch) of the voice coil outward from the voice coil under the same conditions The
portion of the cone is compressed by the O, OO04 layer. As can be seen from this, a cone with
9.1 cm (3 layers 2 inches) inside is a paper cone with a diameter of B, 9 cm (3, 5 inches) and
14.0 cm (5, 5 inches)- Twist about 16 times more than the part of. It is understood that the strain
in question here is generated at a volume sufficient to cause damage to the human ear due to
weak compression or tension that can not be measured. U.S. Pat. No. 1,786,279 (Wolf) and U.S.
Pat. No. 2,643,727 (Leon) disclose a reflection mechanism of a speaker system. However, these
patents show a reflection mechanism that extends across the central portion of the speaker, so
the reflection mechanism reflects almost all the sound output from the speaker. Thus, such a
reflection mechanism has been unable to "determine" the sound emitted from the speaker. U.S.
Pat. Nos. 2,037,185 (Salas) and 27,170.47 (Bookman) both disclose a loudspeaker system having
a damper-like member mounted near the center of the speaker cone. The patent does not
disclose the use of a Danno (one member combined with a reflective mechanism and put in place
to reflect only the sound from the outer portion of the speaker cone at least 90 ° away from the
EndPage: 3 The present invention comprises: (a) an outer case forming a cabinet with a front wall
having an opening from which sound is emitted, and (b) an outer case adjacent to the sound
emitting opening, attached to the outer case Breaking the loudspeaker cone flared outward and
forward, the loudspeaker having a central portion that produces a distorted sound during
operation, and an external portion that emits a substantially undistorted sound during operation,
and From the outer portion of the loudspeaker cone such that a number of reflection
mechanisms are directed outward of the outer box and at an angle of at least 90 ° from a line
extending forwardly of the outer portion of the loudspeaker cone A loudspeaker system of the
type configured to reflect only the undistorted sound. With this loudspeaker system, the cone is
90 ° away from the listener so that the distorted sound coming out of the central part is not
directly directed towards the listener. At least one reflector #I is placed to reflect only the
undistorted sound from the outer part of the speaker cone to the listener side and distribute this
sound over a large area on the listener side. Preferably, damper pads are placed along the
woofern ar-n axis along with the tiles, interrupting strain on the central cone and removing it.
Proper placement of these components produces a virtually distortion-free sound, good
distribution at the top of the woofer's frequency range, close to the ideal response curve, and
cheap and simple A loudspeaker system may be provided. An embodiment of the present
invention will now be described with reference to the drawings, but the invention is not limited to
only this embodiment. In FIG. 1 which is shown in detail so that the present invention can be
better understood, It is formed using a material or other suitable material. A low frequency
speaker or woofer 11, an intermediate frequency or midrange speaker 12 and a high frequency
speaker or tweeter 13 are placed in the housing. The paper cone 14 is oscillated by the current
induced in the voice coil 16 under the action of the magnetic field in the woofer-11TIi magnet
17. The voice coil 16 generates a relatively heavy force on a relatively weak paper cone, while
the cone 14 is required to be light, and is therefore made thin to minimize inertial forces.
Because the force applied to the cone 14 is strong and the cone strength is low, the stress
generated by the voice coil 16 causes the cone 14 to be slightly deformed or distorted. When the
central portion of the cone 14 is deformed, a sound including distortion is produced from the
central portion of the cone in a region indicated by "X" in FIG.
Since the damper pad 18 is fixedly supported by the bracket 19, it absorbs most of the distortion
sound emitted from the central cone. Even the faint distortion sound that spreads through the
pad propagates in a straight line, so most of it is consumed and emitted away from the listener. A
reflecting mechanism 21 fixedly supported by a stud 22 is mounted in front of and near the
speaker cone 14. The reflector 21 is positioned and configured to reflect only the sound from the
undistorted portion of the woofer cone 14 designated rYJ. In the most preferred embodiment,
this reflection mechanism 21 has a thin sheet of fiber or other sound absorbing material tissue
surface 23 so that the reflection of the sound at the top of the response curve of the woofer is
appropriate. Gives an ideal response curve which is reduced by By using a suitably shaped
reflection mechanism, preferably by using a parabolic reflection mechanism, a more nearly linear
speech frequency than that of the woofer 11 can be emitted into the broad band indicated by "z".
The emission at the top of the woofer frequency is usually low, as most mid-range speakers
produce good sound. It should be understood that although a reflection mechanism of a
deformed parabola as shown in FIG. 1 is preferable in FIG. 1, good results can be obtained by
using reflection mechanisms having various other shapes. For example, FIG. 2 shows a V-shaped
reflection mechanism 21m, which can be used to obtain desirable results. The reflector may be
configured to have two separate surfaces adapted to cooperate with one another to act as a
concave reflector. An example of this type of multiple EndPage: 4 combined reflection
mechanism is shown in FIG. 6, in which the two flat support-like reflection mechanisms 21b
cooperate to form a concave reflection mechanism and are held by the support bracket 20. FIG. 4
shows another embodiment of the composite reflecting mechanism, in which the bracket 24
holds the two curved reflecting members 21c in a fixed manner so that they cooperate to
function as a concave reflecting mechanism. It is provided. In some cases, it is desirable to use
one or more E woofers -11. The advantages of the present invention are equally applicable to
speaker systems having more than one woofer, as shown in FIG. In the embodiment shown in
FIG. 5, two reflection mechanisms are used, but the upper end of the woofer's response curve can
provide an excellent frequency distribution. It is not necessary to provide one or more woofers in
order to obtain excellent low- and mid-range distribution characteristics by using one or more
reflecting mechanisms 21.
FIG. 6 shows that one reflecting mechanism 21 is placed on each side of the woofer -11. In FIG.
6, a bracket 26 straddles between the reflecting mechanisms 21 to hold the damper pad 18 in an
appropriate position. In the graph of FIG. 7, the approximate response curve of a 10-inch
acoustic suspension speaker directed to the listener side is shown by the solid line 27 and is the
same speaker rotated and placed against the listener The approximate response curve of is
shown by the dotted line 28. Most conventional woofers have distortion in the center cone, so
the highest volume of the reproduced sound can not be obtained at the lowest audio frequency,
and the response with the high volume sound produced at about 1.000 cps as shown by the solid
line 27 It has peaks or sharp overhangs in the curve. Peaks or overhangs in the woofer's
response curve occur just below the intersection between the woofer's response curve 27 and
the midrange speaker's response curve 29 and can hardly be removed by the electrical crossover
network Produces high notes. The response curve of the high frequency speaker or tweeter is
shown at 31. The smooth, sharp response curve obtained by the loudspeaker according to the
invention is shown by the dotted line 62. As mentioned above, the loudspeaker according to the
invention can reproduce undistorted sound, and by keeping the mass of the speaker cone
sufficiently low, distortion can be prevented from occurring to an appreciable extent. Also,
although the loudspeaker system according to the present invention is simple in construction,
inexpensive to manufacture and can save assembly time as well as labor, the present invention
has been described with respect to one embodiment thereof, but Therefore, it is obvious that
those who belong to the relevant technical field may make various modifications and alterations.
4. Brief description of the drawings Fig. 1 is a longitudinal sectional view showing an
embodiment of a loudspeaker system according to the present invention having a woofer not
facing the listener and a reflection mechanism and a damper pad fixed thereto; 2, 3 and 4 are
partial sectional views showing another embodiment of the reflection mechanism, respectively;
FIG. 5 is a loudspeaker according to the invention having two reflection members and two
woofers to which a damper pad is fixed. FIG. 6 shows an embodiment of a loudspeaker system
according to the invention with two reflection mechanisms attached to a single woofer to
improve the distribution of the midrange frequency; FIG. 7 shows a 10-inch acoustic suspension
speaker directed towards the side of the listener and towards the windward side of the listener
and an improved anti-cooperation cooperating therewith Is a graph showing the approximate
response curve mechanism. DESCRIPTION OF SYMBOLS 10 ... Outer case 11 ... Low frequency
speaker or woofer -112 ... 1 car in the middle band, 16 ... High frequency speaker or tweeter 114
... Cone, 16 -... voice coil, 18 ・ ・ ・ Timber pad, 21 ・ ・ ・ Reflecting mechanism, agent patent
attorney Shozo Taniyama Shozo (other 2 people); EndPage: 5
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